Investigation into the Restoration and Modification Process of a 3D Printer

In 2020, I found a local listing on for a broken 3D Printer on Freecycle, a website that allows people in your local community to put up a listing for something they no longer have a need for (Freecycle, 2021). I had no previous experience with 3D Printing, so I seized this opportunity to restore and upgrade the 3D printer to create a functional and reliable machine. This investigation will outline all of the modifications I have made to the printer alongside the process of how I executed this project.

There are many different types of 3D printing technology, but the printer I have restored uses a process known as Fused Deposition Modelling (FDM). FDM is a method of additive manufacturing where layers of a thermoplastic are fused together in a pattern to create an object (Grames, 2020). In order to create objects, a piece of software known as a ‘slicer’ converts a 3D model into hundreds of layers and generates code that the printer can understand. These layers are then sent to the printer which will proceed to move its 3D motion system and deposit every layer on top of the next until a model is finished.

The model of printer that I have restored is a Solidoodle 3 and it was built in 2012 by Solidoodle. However, Solidoodle suspended operations in 2016 (Sam, 2016) meaning that documentation about how to fix the printer was scarce and there were no available replacement parts to buy. Through some online research, I was able to find the 3D model for the part that was broken, and I got a friend to print it out for me. I installed this part to get the printer functioning and I performed a test print. However, after the first test print it was clear that the technology was outdated, and I proceeded to upgrade it to a modern standard to increase its reliability and the quality of the prints it produced.

The first part of the printer that I upgraded was the extruder. The extruder is the part of the printer where the plastic gets drawn in, melted, and pushed out (Anderson, 2016). It is built up from two main components: the hot end and a stepper motor. The hot end is the part of the extruder that reaches the temperatures required to melt the plastic and connected to it is a thermistor and a motor to feed in the plastic filament. The original hot end in the Solidoodle 3 used a thermistor that lacked accuracy with a temperature tolerance reading of roughly plus or minus 20°C (SoliWiki, 2016). One limitation of this design is that the high degree of inaccuracy made it very difficult to fine tune the temperature for a specific plastic. As a result, the parts the printer produced would have often printed at a temperature too hot or too cold resulting in a variation of strength and dimensional accuracy. In addition to this, the hot end would often clog due to the lack of active cooling. It is crucial that the hot end has adequate cooling to ensure that the plastic filament being fed into it does not begin to melt before it reaches the melt zone (Stevenson, 2016), and the original hot end lacked any active cooling fan to assist in this. For these reasons, I upgraded to the E3D V6 hot end. This new hot end utilises a modern, reliable thermistor for precisely monitoring temperatures and it uses a powerful axial fan to actively cool the hot end. It can also reach temperatures as high as 285°C (E3D, 2021) because of its all-metal design compared to the original hot end’s maximum temperature of 220°C.

In order to fit this upgrade, I needed a different mount for the hot end. One of the perks of the 3D printing community is that individuals can share their own 3D designs with each other. After researching upgrades for the Solidoodle 3, I found the SoliForum website and a design for a hot end mount that claimed to fit the E3D V6 hot end by a user called ‘Lawsy’. I printed out this design and from my experience fitting the mount, the design did work with the E3D V6. Pictured below on the right is the original ‘jigsaw’ extruder mount made from layers of acrylic and pictured on the left is the MK6 design (Lawsy, 2013) made from PETG plastic. The new mount design (pictured left) is stronger than the original acrylic design because it is not as brittle when exposed to the high temperature printing environment. This new open design also makes it easier to access the motor gears (circled), allowing for easier maintenance.

Solidoodle 3 Extruders

Through installing this upgrade, the extruder has drastically improved as it can now print up to 285°C, accurately measure temperature, and be easily maintained due to the openness of the new mount.

As the E3D V6 hot end is not an officially supported part for the Solidoodle 3, I had to calibrate it to work with this machine. To do this, I printed out multiple revisions of the 3D ‘benchy’ to quantify this process. The 3D benchy is a model designed to benchmark a 3D printer (3D benchy, 2020) and it is widely regarded as an accurate measure of how well a 3D printer can print challenging geometrical features.

My initial print with the E3D V6 hot end resulted in the amplification of a surface artefact known as ‘moiré’. When 3D printing, surface artefacts are different patterns that appear on the surface of your prints as a result of a mechanical or electrical component not being properly calibrated (Dwamena, no date). This artefact became visible because the E3D V6 was manufactured to tighter tolerances than the original. Pictured below is my first print with the E3D V6 hot end.

Benchy with Moire

The cause of this ‘moiré’ effect was the result of the extruder motor stepper driver with a step rate of 1/16 not being able to send enough pulses to the printer. The step rate is the highest speed at which the electronics can send pulses to the motor (RepRap, 2017). To fix this, I upgraded to the DRV8825 driver with a step rate of 1/32 so that the necessary number of pulses could be provided to the extruder motor. Pictured below is my first print with this new driver.

3D printed benchy

The higher step rate 1/32 significantly reduced the ‘moiré’ pattern but it was still there and through further calibrating the voltage of the driver I was able to eliminate the problem.

3D printed benchy

Through calibrating the E3D V6 hot end and implementing the new stepper driver the print surface became far smoother.

In order for the extruder to move and lay down the plastic in different patterns to build up an object, a 3D motion system is required. The Solidoodle 3 uses a cartesian design to move the print head (pictured below). One stationary motor moves the Y axis back and forth whilst another moving motor controls motion on the X axis. Another Z motor will turn a threaded rod to move the print bed down every time a layer is completed.

I upgraded this cartesian motion system from the original design to improve the rigidity of the X and Y axes. The original X and Y axes used 8mm rods with brass bushings that were not designed for linear motion. The rods had poor tolerances and they had worn out over years of use. This created play between the rods and the bushings making the motion system unprecise. To solve these issues, I replaced the X and Y carriage with a new design (Lawsy, 2013 (2)). This design uses brackets that fit LM8UU ball bearings and 8mm hardened steel rods. The rods I sourced have a standard h6 tolerance of plus or minus 0.02mm compared to the original +0.2mm tolerance meaning that they will not bind the new bearings. The rods are also case hardened so they will have a far greater lifetime than the original rods. The LM8UU ball bearings improve the grip to the rods by eliminating any side-to-side movement. The new brackets also make tensioning the belts that the motors pull a much easier process. (Lawsy, 2013 (2)). The source claims that the carriages will glide smoothly without lube and adjustment for x-axis belt tension. From my experience using these carriages, these claims are true, and the assembly process was simple. Through upgrading to this design, the printer now has a precise motion system that will reduce mechanical surface artefacts whilst being easy to maintain.

In addition to the E3D V6 hot end and the new X and Y carriage design, I made a few other minor modifications to help the ease of use of the printer. The stock printer used a machined aluminium heated bed with a layer of Kapton tape to help the plastic to adhere. The bed is the part of the printer that the object is built up on (Anderson, 2013) and in the Solidoodle 3 it is heated. In the state this printer was given to me, the Kapton tape had begun to wear down which limited the adhesion of the plastic and I solved this by replacing the Kapton tape with a borosilicate glass sheet. Borosilicate is resistant to high temperatures (Matmatch, 2021) and it does not expand as much as other types of glass making it a suitable and robust platform for a build plate. It is also easily removed which is a useful feature once a print is finished. The extruder has many wires coming out from it, and these wires were originally bundled together by a braided PET sleeve. Often whilst printing, this sleeve would bend and get bundled together at the corner of the printer creating unnecessary kinks in the wires. To fix this I printed out a cable chain to hold all of the cables in place and prevent this from happening (Lawsy, 2013 (3)).

Although I upgraded the X and Y axes, the Z axis was still unstable. This instability was the result of the bed frame moving from side to side every layer because it was only supported at the back of the frame. The bed frame is also made out of wood which expands when exposed to the heated bed (Hendershot, 1924) and this expansion and contraction meant that it was no longer as rigid. As a result, every layer was not perfectly laid on top of the next. This resulted in the mechanical surface artefact of Z ‘banding’. To counteract this, I designed my own mount to screw into the front of the bed frame to prevent side to side wobble (outlined in red below). This mount clamps onto a 4mm rod and has bearing holders (pictured below) at the end so that it can smoothly move down the sides of the printer frame. This bracket has significantly reduced the Z banding artefact on the prints by removing most of the movement at the front of the printer.

Solidoodle 3 Bed bracket

Despite these upgrades, there are still a few areas that I would like to add upgrades in order to further improve the usability and performance of the printer. In its current state, the printer is very noisy. This is due to a mixture of the vibrations generated by the stepper motor drivers and the hot end cooling fan. To eliminate the stepper motor sound, I could use a different control board with newer silent stepper drivers coupled with a quieter fan. The printer uses a 12V bed to assist in helping the filament to adhere. However, to heat this to the required temperatures of certain filaments like ABS of 90C it takes around 15 minutes compared to the hot end which takes about 3 minutes to reach temperature. Given more time, I would install a newer heated bed system that could heat up much quicker to reduce the overall time it takes to begin a print.

Through the process of upgrading this printer, I have restored a piece of technology from 2012 to a functional and reliable machine. From the state I received the printer, it now has a precise motion system with parts built for longevity. It also has a hot end that can maintain higher temperatures than it originally could. This enables the printer to print a wider range of materials such as Nylon and ABS. The bed frame is now more mechanically stable, reducing the impact of Z banding.

3D printed calibration cubes

Pictured above is a comparison between my first successful test print and my latest. The latest test print is dimensionally accurate, with clearly defined layer lines making it a far greater quality of print. The modified printer is also capable of repeating these results.

It has been really rewarding seeing this piece of equipment come back to life and learning the ins and outs of how this printer functions. Since restoring this printer, I have brought another 3D Printer and this process has exposed me to many other communities of likeminded individuals doing similar projects. Although I could have bought a cheaper prebuilt printer, I would not have gotten the same in depth understanding of how 3D printer’s work. The technical knowledge I have gained from this project will enable me to maintain this printer and perform future upgrades to continue the development of this 3D printer.

Bibliography


Anderson, T. (2016) ‘Anatomy of a 3D printer: how does a 3D printer work?’, MatterHackers, 4 February. Available here [Accessed 04/04/2021]

Dwamena, M. (no date) ‘How to fix 3D prints that have vertical lines/banding’. Available here [Accessed: 04/04/2021]

E3D (2021) Thermistor cartridge. Available here [Accessed: 04/04/2021]

Freecycle (2021) History & background information. Available here [Accessed 04/04/2021]

Grames, E. (2020) ‘Fused Deposition Modelling: an introduction’, ALL3DP, November. Available here" [Accessed: 04/04/2021]

Hendershot. O.P. (1924) ‘Thermal expansion of wood’, Science, 60(1559), 456-457. Available here

Lawsy (1). (2013) ‘Solidoodle jigsaw replacement extruder mk5’, Thingiverse, 01 July. Available here [Accessed 04/04/2021]

Lawsy (2). (2013) ‘Solidoodle replacement carriages’, Thingiverse, 15 June. Available here [Accessed 04/04/2021]

Lawsy (2). (2013) ‘Solidoodle cable chain’, Thingiverse, 17 June. Available here [Accessed 04/04/2021]

Matmatch (2021) Borosilicate glass: properties, production and applications. Available here [Accessed 04/04/2021]

RepRap (2017) Step rates. Available here [Accessed: 04/04/2021]

Sam. (2016) ‘Solidoodle announces suspension of operations’, Solidoodle, 28 March. Available here [Accessed: 04/04/2021]

Stevenson, K. (2016) ‘The critical importance of cooling during plastic 3D printing’, Fabbaloo, 14 November. Available here [Accessed: 04/04/2021]

SoliWiki (2016) E3D extruder. Available here [Accessed: 20/12/2021]

3DBenchy (2020) About #3DBenchy. Available here [Accessed: 04/04/2021]

Walker A. (2013) ‘3D printing for dummies: how do they work?’, Available here

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© 2022 Richard Geoghegan